Display Selection Button Light Guide for Accurate Touch Detection
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Solution Overview
Problem
Conventional switch units in vending machines and similar devices require a complex configuration with proximity sensors or light projecting and receiving units to detect finger proximity or touch, which can be cumbersome and less efficient.
Innovation Solution
A simplified switch unit configuration using a first light projecting unit, a light guide plate with prisms, and multiple light receiving units, where the light guide plate directs light from the projecting unit to the prisms, which reflect light towards the user's finger, and the light receiving units detect the reflected light to determine finger proximity or touch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a proximity sensor or light projecting/receiving unit is used to detect finger proximity or touch, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines the light projecting unit and light receiving unit into a single integrated structure where the light receiving unit is positioned behind the light guide plate. This merging eliminates the need for separate sensor assemblies while maintaining detection functionality, thereby reducing device complexity without sacrificing detection accuracy.
Solution Approach 2:
The light guide plate serves multiple functions: it guides light from the projecting unit, reflects light toward the finger, and allows the receiving unit to detect reflected light. This multi-functionality consolidates what would otherwise require separate components, reducing overall device complexity while preserving measurement precision.
2Measurement precision
If multiple light receiving units are provided at different distances from the light projecting unit, then detection sensitivity is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by positioning light receiving units at specific locations behind the light guide plate where they can optimally receive reflected light. The detection sensitivity is enhanced by strategically placing receivers at different distances, with each position tailored to capture light reflection characteristics specific to that location, thereby improving overall detection sensitivity without requiring a uniform complex arrangement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows for accurate detection of finger proximity or touch with a simplified setup, ensuring reliable operation in vending machines and similar devices while reducing complexity and improving efficiency.
Implementation Method 1
a plurality of first prisms that reflect the light incident from the incident surface toward the side approached or touched by the finger
Data Source
AI summary
A display selection button 10 comprises a light projecting unit 21, a light guide plate 13, a plurality of light receiving units 22, and a control unit 30. The light guide plate 13 has an incident surface 13a to which the light projected from the light projecting unit 21 incident, a plurality of prisms 13d that reflect incident light toward the finger side and are provided at positions corresponding to push buttons 10c, and an exit surface 13b that emits the light reflected in the direction in which the finger approaches. The light receiving units 22 are provided at positions corresponding to the push buttons 10c and receive light reflected from a finger. The light receiving unit 22 have higher detection sensitivity as a distance from the light projecting unit 21 increases so as to compensate for the amount of light that decreases depending on the distance from the light projecting unit 21.